We report the absorption spectrum of natural and isotopicaly enriched samples of $N_{2}O$ observed from 1080 to $1330 cm^{-1}$ using the Fourier Transform spectrometer at the University of Paris. Measurements were made at temperatures up to $250^{\circ}C$. Of special interest are the $\ell$-doublets. In several bands it was possible to resolve low-J P-branch $\ell$-doublets where the cc components had higher frequencies than the dd components. Resolved $\ell$-doublets could be seen in both the P and R branches in one $\Phi \Phi$ band.